1.前言
我们想写自己的starter,该怎么下手呢?需要了解两个问题:
1、这个场景需要使用到的依赖是什么?
2、如何编写自动配置
2.如何编写自动配置
- 自动装配Bean;
– 自动装配使用配置类(@Configuration)结合Spring4 提供的条件判断注解
@Conditional及Spring Boot的派生注解如@ConditionOnClass完成; - 配置自动装配Bean;
– 将标注@Configuration的自动配置类,放在classpath下METAINF/spring.factories文件中
自动装配顺序
– 在特定自动装配Class之前
• @AutoConfigureBefore
– 在特定自动装配Class之后
• @AutoConfigureAfter
– 指定顺序
• @AutoConfigureOrder
启动器(starter)
– 启动器模块是一个空 JAR 文件,仅提供辅助性依赖管理,这些依赖可能用于自动
装配或者其他类库
– 命名规约:
• 推荐使用以下命名规约;
• 官方命名空间
– 前缀:“ spring-boot-starter-”
– 模式:spring-boot-starter-模块名
– 举例:spring-boot-starter-web、 spring-boot-starter-actuator、 spring-boot-starter-jdbc
• 自定义命名空间
– 后缀:“ -spring-boot-starter”
– 模式:模块-spring-boot-starter
– 举例:mybatis-spring-boot-starter
@Configuration //指定这个类是一个配置类
@ConditionalOnXXX //在指定条件成立的情况下自动配置类生效
@AutoConfigureAfter //指定自动配置类的顺序
@Bean //给容器中添加组件
@ConfigurationPropertie结合相关xxxProperties类来绑定相关的配置
@EnableConfigurationProperties //让xxxProperties生效加入到容器中
自动配置类要能加载
将需要启动就加载的自动配置类,配置在META‐INF/spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
3.模式
启动器只用来做依赖导入;
专门来写一个自动配置模块;
启动器依赖自动配置;别人只需要引入启动器(starter)
mybatis-spring-boot-starter;自定义启动器名-spring-boot-starter
4.创建步骤
首先我们创建两个项目
第一个项目是启动器项目,也是空项目,只提供给其他项目引用使用,在他的pom文件添加依赖autoconfiguration
1)启动器模块
项目结构如图:
<?xml version="1.0" encoding="UTF‐8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema‐instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/xsd/maven‐4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.atguigu.starter</groupId>
<artifactId>atguigu‐spring‐boot‐starter</artifactId>
<version>1.0‐SNAPSHOT</version>
<!‐‐启动器‐‐>
<dependencies>
<!‐‐引入自动配置模块‐‐>
<dependency>
<groupId>com.atguigu.starter</groupId>
<artifactId>atguigu‐spring‐boot‐starter‐autoconfigurer</artifactId>
<version>0.0.1‐SNAPSHOT</version>
</dependency>
</dependencies>
</project>
第二个项目是自动配置项目,主要功能是提供了自动配置,按照我们上面的步骤配置就行。
2)自动配置模块
项目结构如图:
<?xml version="1.0" encoding="UTF‐8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema‐instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven‐
4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.atguigu.starter</groupId>
<artifactId>atguigu‐spring‐boot‐starter‐autoconfigurer</artifactId>
<version>0.0.1‐SNAPSHOT</version>
<packaging>jar</packaging>
<name>atguigu‐spring‐boot‐starter‐autoconfigurer</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring‐boot‐starter‐parent</artifactId>
<version>1.5.10.RELEASE</version>
<relativePath/> <!‐‐ lookup parent from repository ‐‐>
</parent>
<properties>
<project.build.sourceEncoding>UTF‐8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF‐8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<!‐‐引入spring‐boot‐starter;所有starter的基本配置‐‐>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring‐boot‐starter</artifactId>
</dependency>
</dependencies>
</project>
package com.atguigu.starter;
import org.springframework.boot.context.properties.ConfigurationProperties;
@ConfigurationProperties(prefix = "atguigu.hello")
public class HelloProperties {
private String prefix;
private String suffix;
public String getPrefix() {
return prefix;
}
public void setPrefix(String prefix) {
this.prefix = prefix;
}
public String getSuffix() {
return suffix;
}
public void setSuffix(String suffix) {
this.suffix = suffix;
}
}
package com.atguigu.starter;
public class HelloService {
HelloProperties helloProperties;
public HelloProperties getHelloProperties() {
return helloProperties;
}
public void setHelloProperties(HelloProperties helloProperties) {
this.helloProperties = helloProperties;
}
public String sayHellAtguigu(String name){
return helloProperties.getPrefix()+"‐" +name + helloProperties.getSuffix();
}
}
package com.atguigu.starter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConditionalOnWebApplication //web应用才生效
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfiguration {
@Autowired
HelloProperties helloProperties;
@Bean
public HelloService helloService(){
HelloService service = new HelloService();
service.setHelloProperties(helloProperties);
return service;
}
}
在atguigu-spring-boot-starter-autoconfigurer/src/main/resources/META-INF/spring.factories添加配置:
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.atguigu.starter.HelloServiceAutoConfiguration
因为自动配置类要能加载将需要启动就加载的自动配置类,配置在META‐INF/spring.factories
添加测试项目:
目录结构如图:
package com.atguigu.springboot.controller;
import com.atguigu.starter.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
@RestController
public class HelloController {
@Autowired
HelloService helloService;
@GetMapping("/hello")
public String hello(){
return helloService.sayHellAtguigu("haha");
}
}
atguigu.hello.prefix=ATGUIGU
atguigu.hello.suffix=HELLO WORLD
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.atguigu</groupId>
<artifactId>spring-boot-08-starter-test</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>spring-boot-08-starter-test</name>
<description>Demo project for Spring Boot</description>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.5.10.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<!--引入自定义的starter-->
<dependency>
<groupId>com.atguigu.starter</groupId>
<artifactId>atguigu-spring-boot-starter</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
访问地址localhost:8080/hello看结果:
配置生效。
5.更多SpringBoot整合示例
https://github.com/spring-projects/spring-boot/tree/master/spring-boot-samples